Nicole Kidman

"She says turn on the light, otherwise it can't be seen/She's got cheekbones like geometry and eyes like sin" - Perfect Skin, by Lloyd Cole

cold Nicole Kidman has a way of turning men's brains to mush. Critics go ga-ga for her: this was the woman who inspired that famous "theatrical Viagra" review when she starred in The Blue Room in the West End. Guardian film critic Peter Bradshaw fancied he could "hear the faint crackle of her stockings" as she entered The Golden Compass. The usually estimable David Thomson went so far as to write a tell-all book about her stranglehold on his fevered imagination, including a three-page fantasy involving a brothel, a white bra "a size or two too small", a Gestapo officer and "an elderly Chinaman".

So let's admit that Kidman is hot and get it over with. But it's equally true to say that she's cold. Her characters are invariably rational and calculating, not warm and impetuous. This remains true even when she's playing not-so-smart (in To Die For, for instance; still a defining role).

Look back over the 30 or so movies she's made since Dead Calm in 1989 and you'd be hard pressed to find evidence of chemistry with anyone - least of all in the three pictures she made with Tom Cruise. She had more rapport with her husband in Birth - dead and reborn as a ten-year-old child. As Dead Calm demonstrated from the outset, Kidman is a remarkably self-sufficient presence, enterprising and intelligent enough to save her own skin. It's rare that she pays more than lip service to anyone else's.

Moulin Rouge This explains why she was such bad casting as the last vestige of humanity in The Invasion - she comes across as part pod person already. Conversely, it suggests why Phillip Pullman says he always imagined Kidman playing the glamorous Marisa Coulter in The Golden Compass, and why she's so good in it. Of course, we don't insist that actors should be emotionally available. What's more, 50 or 60 years ago the silver screen was dominated by women like this: Joan Crawford, for instance; or Barbara Stanwyck. In another era, she might have made a formidable femme fatale. Today, in our more touchy-feely times, that hardness must be counted a limitation.

Kidman can be desperately unconvincing when she's called on to play someone with less of her wherewithal - the gentle impracticality required of her in certain scenes in Cold Mountain for example, or as needy white trash Faunia Farley in The Human Stain. When she's flailing she can be mannered and heavy. She's also quite capable of blanding out completely playing pert and pretty in pass-me-the-paycheck fluff like The Stepford Wives and Bewitched.

Since the split from Cruise - and the determined, worldwide media charm offensive she put herself through in its wake - Kidman made herself, if not the biggest female star in the world (I guess Julia Roberts and Angelina Jolie would have something to say about that) then certainly the most sought after. And she accomplished this more than anything by communicating her hunger for challenge and good work.

That is: over a three-year period she worked with an Aussie (Baz Luhrmann on Moulin Rouge!); a Spaniard (Alejandro Amenabar on The Others); two Brits (Jez Butterworth and Stephen Daldry, on Birthday Girl and The Hours, respectively); and a crazy Dane (Lars Von Trier on Dogville). Hardly a safe commercial choice in the lot of them, yet she came away with back to back Best Actress nominations, a win for The Hours, a couple of bone fide hits, and enormous credibility.

Australia Her instincts (or her luck) haven't been so unerring since, but she continues to take on risky projects like Birth, Fur, and this week's brilliantly noxious Margot at the Wedding (one of her best ever performances in a film that has made less than $2 million at the US box office). Her career would look a lot more solid of if the supposedly safer mainstream movies had lived up to expectations. With the failure of The Golden Compass in the US market, the $10 million paychecks may be gone for good.

Kidman is 40 now, and expecting a child this summer with new husband Keith Urban. These are unsparing times for any actress: the internet gossip sites, the paparazzi, and even advances in movie technology seem to demand perfection at every turn (amusingly, Cargo brought out a new line of cosmetics called blu_ray, promising skin fit for High Definition). But you can't win: Kidman's fair complexion only fuels further rumour and speculation about plastic surgery and botox injections (which she has denied).

So far she's managed to ride over the innuendo - somehow she manages to give next to nothing away in interviews and still come across as authentically down to earth. For all the thousands of magazine cover stories from the last decade we're still in the dark about her marriage to Tom Cruise, and Andrew Morton's book doesn't shed much light on what went on there either.

Right now she has just one more movie in the can: Baz Luhrmann's period epic Australia, in which she stars. Several other projects have failed to come together, so it remains to be seen if she can continue to roam so far and wide, or whether Hollywood will look for a younger model. Not that she seems tainted by box office failures, certainly not in the eyes of filmmakers or fans. Kidman's adventurous streak has served her well: in Margot; in Birth; Dogville; The Hours and Eyes Wide Shut we can see that she's never better than when she dares to show us her ugly side.

Tom Charity
tom.charity@lovefilm.com